Centrifugal device



g- 5, 1940- w. SCHAELCHLIN ET AL 2 0, 87

CENTRIFUGAL; DEVICE Filed March 21, 1939 :1; man a WITNESSES: 3/

INVENTOR 5 MG /2er 5c/7ae/c/7 //h g 5 fiea er/cK- E .Z'Dawls. fimyni. WWW

ATTORNEY Patented Aug. 6, 1940 UNITED STATES PATENT OFFICE CENTRIFUGAL DEVICE East Pittsburgh, Pa.,

sylvania Application March 21,

13 Claims.

Our invention relates to centrifugal devices, and it has particular relation to the rotor member of a centrifugal switch such as is utilized on relatively small, self-starting, single-phase capacitor-motors.

Centrifugal switches of the class referred to have requirements which, in some senses, are rather exacting, but which, in other senses, are not so exacting. Since quantity-production methods are applied to the manufacture of such switches, the matter of cost is of paramount consideration, attention being paid to even very small fractions of a cent. In many instances, as

in refrigerator motors and in many other smallmotor applications, the matter of extreme silencev of operation is also of paramount importance.

A peculiar characteristic of a capacitor motor, which is a type of motor finding more and more use in small, single-phase motor-applications, is that the centrifugal switch cannot be permitted to reclose its contacts, when the motor is decelerating, until the motor has decelerated to a rather low speed, as otherwise the motor is likely to self-excite itself, as a result of its residual magnetism and the capacitance which is in series with the capacitor-winding, causing the motor to rapidly stop with an objectionable growling noise.

Another requirement of centrifugal switches of the type under consideration is that the same basic parts, for economy in the manufacturing operation, will have to be utilizable over a wide range of speeds, as between 600 and 3600 revolutions per minute, by the simple expedient of changing weights and springs.

A specific object of our invention is the provision of a single-weight rotor of the above-described class which, because it has only a single weight-member can be balanced only in the running position of the centrifugal device. Hovever, because only one weight is utilized, the cost of the centrifugal device can be reduced to an extreme minimum, and hence our preferred form of embodiment is a construction in which the desideratum of an extremely low cost is given a very great preference in the design of the mechanism.

With the foregoing and other objects in view, our invention relates to the parts, structures and combinations hereinafter described and claimed, and illustrated in the accompanying drawing, wherein:

Figure 1 is a side elevational view of a centrifugal switch embodying our invention;

Fig. 2 is a vertical sectional view through the a corporation of Penn- 1939, Serial No. 263,221

rotor member of the centrifugal switch, on a section plane indicated by the line IIII in Fig. 1;

Figs. 3 and 4 are, respectively, front and side views of a Weight-member utilized in our invention;

Figs. 5 and'6 are corresponding views of an interchangeable weight-member of a different thickness and weight, which may be substituted for the weight-member shown in Figs. 3 and 4 in order to adapt the device to a different speedrange, and

Figs. 7, 8 and 9 are elevational views of different interchangeable springs having different stiffnesses, for adapting the device to different speed-ranges.

A centrifugal switch of the type to which our invention relates consists essentially of two parts. One is the so-called stationary part, or contactmaking member 2, and the other is the rotating part or centrifugal speed-responsive device proper, as indicated at 3. Our invention relates more particularly to the latter part, but in order to afford a complete understanding of the invention, the stationary part 2 has been somewhat diagrammatically illustrated in the drawing, as comprising a stationarily mounted housing-portion 4, which encircles the shaft 5 in spaced relation thereto, and which cooperates with a sheetmetal contact-spring 6 which also encircles the shaft in spaced relation thereto. In the illustrated form of embodiment, as shown in Fig. l, the bottom portion of the contact-spring 6 is fixedly secured to the stator housing-portion 4 and constitutes one of the terminals of the spring contact-mechanism, as indicated at 7. The top portion of the contact-spring B terminates in a contacting tip 8 which is adapted to be engaged by a stationary contact-member 9 which forms the other terminal of the spring contact-mechanism. The details of the stationary part 2 constitute the subject-matter of an application of Walter Schaelchlin, Serial No. 263,220, filed March 21, 1939, for Contact-mechanism for centrifugal switches.

Our invention relates prmarily to the rotating part 3 of the centrifugal-switch mechanism, and primarily to an improved form of embodiment thereof which reduces the manufacturing cost to the smallest possible minimum.

The rotating part 3, which is the real speed-responsive part of the mechanism, comprises,

among other things, a guide-member H which has a hub-portion I2 which is fixedly secured to the shaft 5. On opposite sides of the shaft, near the hub-portion l2, the guide-member II is provided with lateral flange-portions l3 extending parallel to the shaft, and terminating, at one end, in an inclined surface M. Beyond the inclined surface M, the guide-member H is provided with a bent-portion i5, beyond which there is a substantially radially extending, centrally disposed guide-portion It. On the end of the guide-member li opposite to the guide-portion iii, the guide-member has suflicient material, arranged in any desired manner, to provide a counterweight il for producing dynamic balance during the normal running conditions of the mechanism.

Cooperating with the guide-member ii, there is a single combined weight-and-link member I9 which has an outer portion 253, which constitutes the weight-portion proper, and an angularly related-inner portion 2! which constitutes the linkportion for joining the weight to a slide member 22 which slides axially on the shaft/5, in a manner which will be subsequently described.

The outer and inner portions 20 and 2! of the combined weight-and-link member I9 are disposed at approximately right angles to each other. The outer portion 20], or main weightportion proper, is provided with a slot 23 which embraces the radially extending guide-portion l6.

of the guide-member H, so that this portion of the weight is constrained to move outwardly and inwardly in a substantially radial direction with respect to the shaft 5. The inner or link-portion 2! of the combined weight-and-link member [9 is bifurcated so as to provide two branches extending on opposite sides of the slider member 22,

. said branches having portions 24 restingon the inclined surfaces M, respectively.

The combined weight-and-link member I9 is preferably made from a sheet-metal stamping, and is preferably one of a set of members of different weights, as indicated at 9 and I9 in Figs. 3, 4 and 5, 6, respectively, it being understood that these members have the same external dimensions, so, that they are interchangeable one with another, except that one member is of heavier-gage material, and hence greater mass than the other. The choice of a suitable weight-member from the set of weight-members, provides a very convenient instrument for adapting the speed-responsive mechanism to respond to different shaft-speeds. V

The slider-member 22 is preferably made of a molded light-weight composition-material such as a phenolic condensation product. It has diametrically opposite fiat surfaces 26 on the two sides thereof, said fiat surfaces being provided with grooves 21? extending in a plane at right angles to the shaft, or, more generally, grooves extending in a direction having a large component in a plane at approximately right angles to the shaft 5. The two branches of the bifurcated inner end-portion 2! of the combined weight-andlink member i9 have bent end-portions 28 extending into the respective grooves 21 of the slider-member 22, so as to link the slider-member ber id.

The construction is such that the centrifugal rotor member 3 remains in its illustrated full-line position until the shaft 5 attains a certain critical speed, at which point the combined weight-andlink member l9 begins to move outwardly under the action of centrifugal force. Once started, the combined weight-and-link member continues to move outwardly, with increasing speed even though the speed of rotation of the shaft does not increase, thus insuring a positive snap-action of the switch.

As the outer end 20 of the combined weightand-link member moves outwardly, the springs 3| yieldingly pull back diagonally on it, so as to force the inner end 2| to ride up in contact with the inclined surface M of the, guide-member ll, so that the bifurcated inner ends 2| move up toward the radially extending guide-portion I6, and back toward the back of the guide-member H, as the combined weight-and-link member moves upwardly. The movement of the inner bifurcated ends 24 of the combined weight-andlink member 99 causes the bent end-portions 28 to ride up in the grooves 27 of the slider-member 22, drawing the latter axially backward toward the guide-member H, as the combined weight-and-link member I!) moves outwardly under the influence of centrifugal force.

When the slider-member 22 is thus caused to slide along the shaft 5, its flat end-surface 29 is drawn away from the contact-spring 6, permitting the latter to move, of its own resilience, and open the electrical contact at the points 8 and 9.

The final outward movement of the combined weight-and-link member l9 should be interrupted in some quiet manner, in order to reduce noise. A preferred method of accomplishing this purpose is to bend the extreme end of each groove 27, which is engaged by the bent end-portion 28 of the combined weight-and-linlc member I9 ll. Thus, when the bent end-portions 28, riding in the grooves 27, reach the bent-portions 35 of the grooves, said bent groove-portions 35 will gradually check the movement of the combined weight-and-link member IQ, so that the latter will be brought to standstill without a jar and without noise; I

Our invention is particularly adapted for utilization in a centrifugal switch which is to be applied to a small single-phase capacitor-motor,

and it is quite essential, in such applications,

that the centrifugal switch shall not reclose, on decreasing speeds, until the motor has reached a much lower speed than the speed at which the switch was closed during the starting operation. This requirement is necessitated by the tendency for the capacitor-motor to operate regeneratively, on residual magnetism, aided by self-excitation from the capacitor which is connected in the capacitor-winding, if the capacitor-winding should be reconnected in parallel across the main Winding at too high a speed.

Reference to the dotted-line position offlthe parts in Fig. 1 will show that a relatively large proportion of the pull of the springs 3| is taken up by a partial cam-in action of the combined weight-and-link member l9 when it reachesits out position, or high-speed operative position. At this time, the bifurcated inner end 2| of the combined weight-and-link member l9 rests upon the inclined surface Hi at such an angle that only a very small component of the pull of the coil springs 3! is effective to tend to draw the outer weight-portion 2i) inwardly again. Thus the centrifugal force acting upon this outer weight-portion 20 of the combined weight-andlink member [9 will suffice to hold the combined weight-and-link member IS in its out position until the centrifugal force drops to a very much lower value than was required to initiate the outward movement of the combined weight-and-link member during this starting operation. Also, when the springs finally do start to draw in the combined weight-and-link member l9, they will continue the movement with a rapid snap-action.

The pair of coil springs 3! is preferably one pair of a set of different coil springs 3!, 3i and 3! of different stiifnesses, as illustrated in Figs. 7, 8 and 9, these diiferent springs being readily interchangeable, one with another, so as to provide a ready means for adapting the same essential construction to a large variety of speedranges. From the standpoint of cost-reduction, which is very important on parts for small motors which are made in large numbers, we have made this provision of a single structure which, by simple changes in the combined weight-and-link member G9 or in the coil springs 31, or both, may be adapted for any speed-range which may be required in an entire line of motors of different ratings and speeds.

While We have described our invention in a single embodiment, it will be obvious that many changes may be made without departing from all of the essential features of our invention. We desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

We claim as our invention:

1. A rotor member of a centrifugal device, comprising a guide-member fixed to a rotatable shaft, said guide-member having an approximately radially disposed guide-portion at a considerable distance from the shaft, and having, on each side of said guide-member, an inclinedsurface portion closer to the shaft, said inclinedsurface portions having a component in a direction which is axial with respect to the shaft, a combined weight-and-link member having an outer portion mounted for movement toward and away from the shaft under the guidance of said guide-portion, a slider-member slidably mounted on the shaft, said slider-member having diametrically opposite flat surfaces on the sides thereof, and having, in said respective fiat surfaces, grooves extending in a direction having a large component in a plane at approximately right angles to the shaft, said combined weightand-link member having a bifurcated inner end, the two branches of which have portions extending into said grooves and other portions resting on said inclined-surface portions, and springmeans engaging said combined weight-and-link member to draw the same toward the shaft.

2. The invention as defined in claim 1, characterized by said spring-means comprising a pair of coil springs disposed one on each side of said combined weight-and-link member, each spring engaging its side of the combined weight-andlink member at an intermediate portion thereof to draw the same toward the shaft; the line of action of the spring-means being so disposed that it is nearer dead center with respect to producing movement of said combined weight-and-1ink member in the high-speed position of the parts than in the low-speed position of the parts.

3. The invention as defined in claim 1, characterized by the end of each of said grooves which is engaged by the bifurcated inner end of said combined weight-and-link member in the high-speed position of the parts being curved away from the combined weight-and-link member in a manner to gradually check the outward movement of the combined weight-and-link member.

4. The invention as defined in claim 1, characterized by at least one of the ends of each of said grooves being curved in a manner to gradually check the motion of the combined weightand-link member at that end of its movement.

5. A rotor member of a centrifugal device, comprising a guide-member fixed to a rotatable shaft, said guide-member having an approximately radially disposed guide-portion at a considerable distance from the shaft, and having, on each side of said guide-member, an inclined-surface portion closer to the shaft, said inclinedsurface portions having a component in a direction which is axial with respect to the shaft, 2. weight-portion mounted for movement toward and away from the shaft under the guidance of said guide-portion, a slider-member slidably mounted on the shaft, said slider-member having diametrically opposite fiat surfaces on the sides thereof, and having, in said respective flat surfaces, grooves extending in a direction having a large component in a plane at approximately right angles to the shaft, a link-portion having an outer end in engagement with said weightportion and having a bifurcated inner end the two branches of which have portions extending into said grooves and other portions resting on said inclined-surface portions, and spring-means for drawing said weight-portion and said linkportion toward the low-speed position of the parts.

6. The invention as defined in claim 5, characterized by said spring-means comprising a pair of coil springs disposed one on each side of said link-portion, each spring engaging its side of the link-portion at an intermediate point on said link-portion to draw the same toward the low-speed position of the parts; the line of action of the spring-means being so disposed that it is nearer dead center with respect to producing movement of said weight-portion in the highspeed position of the parts than in the lowspeed position of the parts.

'7. The invention as defined in claim 5, characterized by the end of each of said grooves which is engaged by the bifurcated inner end of said link-portion in the high-speed position of the parts being curved away from the weightportion in a manner to gradually check the out- Ward movements of the Weight-portion and the link-portion.

8. The invention as defined in claim 5, characterized by at least one of the ends of each of said grooves being curved in a manner to gradually check the motion of the link-portion at that end of its movement.

, 9. A rotori member of a centrifugal device, comprising a guide-member fixed to a rotatable shaft, said guide-member having an approximately radially disposed guide-portion at a considerable distance from the shaft, a weight-portion mounted for movement toward and away from the shaft under the guidance of said guideportion, a slider-member slidably mounted on the shaft, said slider-member having diametrically opposite flat surfaces on the sides thereof, and having, in 'said respective flat Surfaces, grooves extending in a direction having a large component in a plane at approximately right link-portion toward the low-speed position oi the parts.

10. The invention as defined in claim 9, characterized by said spring-means comprising a pair of coil springs disposed one on each side of said link-portion, each spring engaging its side of the link-portion at an intermediate point on said link-portion to draw the same toward the low-- speed position of the parts; the line of action of the spring-means being so disposed that it is nearer dead center with respect to producing movement of said link-portion in the high-speed position of the parts than in the low-speed position of the parts.

11. The invention as defined in claim 9, characterized by the end of each of said grooves which is engaged by the bifurcated inner end of said link-portion in the high-speed position of the parts being curved away from the Weightportion in a manner to gradually check the outward movements of the weight-portion and the link-portion,

12. The invention as defined in claim 9, characterized by at least one of theends of each of said grooves being curved in a manner to gradually check the motion of the link-portion at that end of its movement.

13.A rotor member of a centrifugal device, comprising a guide-member fixed to a rotatable shaft, said guide-member having an approximately radially disposed guide-portion at a considerable distance from the shaft, and having, on each side of'said guide member, an inclinedsurface portion closer to the shaft, said inclined- 7 surface portions having a component in a direction which is axial with respect to the shaft, a combined weight-and-link member having an outer portion mounted. for movement toward and away from the shaft under the guidance of said guide-portion, a slider-member slidably mounted on the shaft, said combined weight-and-link member having a bifurcated inner end operatively connected to said slider-member, and spring-means comprising a pair of coil springs disposed one on each side of said combined weight-and-link member, each spring engaging its side of the combined weight-and-link member at an intermediate portion thereof to draw the same toward the shaft; the line of action of the spring-means being so disposed thatit is nearer dead-center with respect to producing movement of said combined weight-and-link member in the high-speed position of the parts than in the low-speed position of the parts.

WALTER SCHAELCHLIN. FREDERICK R. J. DAVIS. 

